
/**
 * Definition for a binary tree node. public class TreeNode { int val; TreeNode
 * left; TreeNode right; TreeNode(int x) { val = x; } }
 */

class TreeNodeInt {
    int val;
    TreeNodeInt left;
    TreeNodeInt right;

    TreeNodeInt(int x) {
        val = x;
    }
}

public class No104 {
    public int maxDepth(TreeNodeInt root) {
        if (root == null) {
            return 0;
        }
        return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
    }
}
